1. Field of the Invention
The present invention relates to a magnetic recording and reproduction apparatus for performing information recording to, and/or information reproduction from, a magnetic tape which is wound around a rotatable head cylinder having a rotatable head over a prescribed angle. In particular, the present invention relates to a magnetic recording and reproduction apparatus having a mechanism for automatically pulling out the magnetic tape from a tape cassette and winding the magnetic tape around the rotatable head cylinder.
2. Description of the Related Art
Recently, size, weight and thickness reduction of video tape recorders have been actively pursued. Especially, a loading mechanism, which has a very complicated structure and includes a large number of components, significantly influences the size and cost of the video tape recorders. The development of the loading mechanism is very important.
Hereinafter, a tape loading mechanism in a conventional magnetic recording and reproduction apparatus will be described. One known loading mechanism for a magnetic recording and reproduction apparatus is disclosed in Japanese Patent No. 2701575, and described with reference to FIGS. 1, 2, 5, 6, 9, 10 and 15 of Japanese Patent No. 2701575. In FIG. 5 of Japanese Patent No. 2701575, reference numeral 14 represents a supply boat, and reference numeral 15 represents a take-in boat. The supply boat 14 and the take-in boat 15 are both tape pull-out members. The supply boat 14 has a supply loading roller post 8 provided thereon, and the take-in boat 15 has first and second take-in roller posts 10 and 11 provided thereon. The supply boat 14 is engaged with a supply ring gear 38 via a supply driving shaft 53, and the take-in boat 15 is engaged with a take-in ring gear 39 FIG. 6) via a take-in driving shaft 55. (FIG. 6 of Japanese Patent No. 2701575 shows the take-in boat 15 in detail.) The supply boat 14 is engaged so as to be movable along a supply loading guide 17, and the take-in boat 15 is engaged so as to be movable along a take-in loading guide 18. The supply boat 14 and the take-in boat 15 move from a pre-loading position (shown in FIG. 1 of Japanese Patent No. 2701575) to a post-loading position (shown in FIG. 2 of Japanese Patent No. 2701575), so as to pull out a tape from a cassette and wind the tape around a rotatable head cylinder (FIG. 1). Reference numeral 86 represents a stopper provided on a chassis 1 for positioning the supply boat 14 at the time of loading the tape. Reference numeral 87 represents a stopper provided on a chassis 1 for positioning the take-in boat 15 at the time of loading the tape.
A tape loading operation of the conventional magnetic recording and reproduction apparatus will be described with reference to FIGS. 9 and 10 of Japanese Patent No. 2701575. In FIGS. 9 and 10, reference numeral 30 represents a motor which is rotatable forward and backward. The rotation of the motor rotates the rings 38 and 39 counterclockwise and clockwise, respectively, via the gears in FIGS. 9 and 10. Thus, the supply boat 14 (FIG. 5) engaged with the supply driving shaft 53 and the take-in boat 15 (FIG. 6) engaged with the take-in driving shaft 55 also rotates counterclockwise and clockwise, thereby pulling the magnetic tape out from the cassette. At a tape pull-out completion position where the magnetic tape has been completely pulled out, the supply boat 14 and the take-in boat 15 are pressed to the stoppers 86 and 87 (FIG. 5), thereby positioning the supply boat 14 and the take-in boat 15.
With reference to FIG. 15 of Japanese Patent No. 2701575, a positioning operation for the supply boat 14 and the take-in boat 15 will be described. FIG. 15 of Japanese Patent No. 2701575 shows a positioning operation of the loading boats in the conventional magnetic recording and reproduction apparatus. Here, the positioning operation of the supply boat 14 will be described as an example.
In FIG. 15 of Japanese Patent No. 2701575, (a) is a plan view, (b) is a side view, (c) is a bottom view, and (d) is a partial cross-sectional view. In FIG. 15, reference numeral 86 represents the stopper as described above. The stopper 86 includes a pin 86a and an inverted cone-shaped (tapered) pressing section 86b provided on the pin 86a. Reference numeral 14a is a V-shaped groove formed at a forward end of the supply boat 14. The V-shaped groove 14a has a ramp surface. A forward portion and a rear portion of the supply boat 14 has a reference plane. The reference planes contact a reference plane of the chassis 1 (FIG. 2 of Japanese Patent No. 2701575), and thus high precision positioning is realized. The reference plane of the chassis 1 is provided in the vicinity of the position of the supply boat 14 at a loading completion position (at which the tape loading is completed). As shown in FIGS. 5 and 15, the supply boat 14 is guided by the supply loading guide 17 as the supply ring gear 38 pivots. The V groove 14a contacts the stopper 86 at the loading completion position, and thus is positioned. More specifically, at the loading completion position, a driving force is constantly applied to the supply boat 14 via the supply driving shaft 53 in a direction of arrow P by the movement of a owing plate 45 (the operation of the swing plate 45 will not be described). Therefore, when the stopper 86 contacts the V-shaped groove 14a, the position of the supply boat 14 is restricted by the V-shaped groove 14a in a horizontal direction perpendicular to the advancing direction of the supply boat 14. (The advancing direction of the supply boat 14 is the direction of arrow P.) Since a force is also applied to the supply boat 14 in a direction of arrow F, the position of the supply boat 14 is restricted in the advancing direction and the opposite direction, and also in a vertical direction perpendicular to the advancing direction.
As described above, in the conventional magnetic recording and reproduction apparatus, the V-shaped grooves of the supply boat 14 and the take-in boat 15 (tape pull-out members) are pressed to the tapered pressing sections of the stoppers 86 and 87 provided on the chassis 1. Thus, the tilt of the loading roller posts 8, 10 and 11 provided in the supply and take-in boats 14 and 15 is precisely kept, and therefore the magnetic tape can be properly wound around the rotatable head cylinder.
The above-described magnetic recording and reproduction apparatus has the following problems.
The position and tilt of the supply boat 14 and the take-in boat 15 are influenced by the variance in the shape of the tapered pressing section of the stoppers 86 and 87. This heavily influences the stable running and protection of the magnetic tape. In order to control the supply boat 14 and the take-in boat 15 with very high precision, the stoppers 86 and 87 need to be processed with high precision. As a result, the stoppers 86 and 87 become expensive.
In the conventional magnetic recording and reproduction apparatus, the stoppers 86 and 87 are formed by being inserted into the chassis 1 by pressure. A slight variance in the height of the stoppers 86 and 87 with respect to the chassis 1 also influences the position and tilt of the supply and take-in boats 14 and 15. This also heavily influences the stable running and protection of the magnetic tape. The height of the stoppers 86 and 87 needs to be controlled with very high precision, and therefore the tape loading mechanism is difficult and expensive to assemble.
The stoppers 86 and 87 are constantly acted on by forces in a direction of pushing the stoppers 86 and 87 down and in a direction of pulling the stoppers 86 and 87 up, As such, the chassis 1 and the stoppers 86 and 87 need to have a certain strength. The portions of the chassis 1 which hold the stoppers 86 and 87 also need to have a certain strength which is kept over time. This inconveniently increases the size of the mechanism.
As described above, the tape loading mechanism in conventional magnetic recording and reproduction apparatuses, represented by the magnetic recording and reproduction apparatus described in Japanese Patent No. 2701575, requires high component precision and high assembly precision in order to control the boats with high precision. In order to guarantee a certain level of strength, the tape loading mechanism is inevitably large in size. For guaranteeing high level of performance and quality of the magnetic recording and reproduction apparatus, the size, weight and cost of the magnetic recording and reproduction apparatus cannot be reduced.